The present invention relates to a current collecting unit including a current collecting rail with at least one connecting pin.
Current collecting units of the above mentioned general type are known in the art. It is known to provide a T-shaped current collecting rail with several pins and wires for connection. Both halves of the transversely located T-legs are shaped respectively to form a sleeve which receives a pin or a wire. The portions of the sleeve are bent upwardly and downwardly from the plane of the current collecting rail to form outer surrounding curves. The connection of the current collecting rail and the pin is advantageously performed by resistance welding and the parts to be welded are located upon contact with electrodes in an electrical current circuit. The electrodes simultaneously press the parts toward one another and contain a material-locking connection at least at the partial welding edges. Heat is obtained directly on the welding edges, and the temperature increase per time unit on the welding points substantially depends on the size of the contact surfaces of the electrodes on the welding material. In the known process one electrode lies on a plane surface of the current collecting rail while the other electrode lies contrary to this on the curved outer surface of the sleeve. Thereby abutment surfaces are produced which considerably differ from one another in their sizes and as a result of it the welding output can be undesirably influenced because of the resulting different heating of both welding zones. Deviations act in an especially disadvantageous manner when it is necessary to connect the materials which are difficult to weld. A list of such materials is presented in the technical journal "Wt.-Z. ind. Fertig. 71 (1981) Nr. 1" on pages 136 and 137.